gprs and edge basics
TRANSCRIPT
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GB_BT03_E1_0 GPRS and EDGE Basics
Course Objectives:
Understand GPRS/EDGE conception
Understand GPRS/EDGE system architecture
State GPRS/EDGE radio frame structure and channels
Understand GPRS/EDGE key technologies
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Contents
1 GPRS Technoo!"#########################################################################################################################################1
1.1 GPRS Definition..................................................................................................................................1
1.2 GPRS eatures.....................................................................................................................................1
1.! GPRS Specifications............................................................................................................................2
1." GPRS #et$ork Structure.....................................................................................................................!
1.% GPRS Protocol Platform......................................................................................................................%
1.%.1 GPRS &ransmission Protocol Platform....................................................................................%
1.%.2 GPRS Signaling Protocol Platform..........................................................................................'
$ GPRS %et&or' (rchitecture#####################################################################################################################13
2.1 (ogical Structure...............................................................................................................................1!
2.1.1 )ain #et$ork Entities...........................................................................................................1"
2.1.2 )ain #et$ork *nterfaces........................................................................................................1'
3 GPRS )ra*e Structure and Radio Channes##########################################################################################$0
!.1 Radio rame Structure.......................................................................................................................2+
!.2 Physical ,hannel...............................................................................................................................2+
!.! (ogical ,hannel.................................................................................................................................21
!.!.1 Packet ,ommon ,ontrol ,hannel -P,,,s0......................................................................21
!.!.2 Packet roadcast ,ontrol ,hannel -P,,0.......................................................................22
!.!.! Packet transport channel0........................................................................................................22
!.!." Packet dedicated control channel0..........................................................................................22
!." ,hannel ,omination........................................................................................................................22
!.% )apping et$een (ogical ,hannels and Physical ,hannels............................................................2!
!.%.1 Uplink ,hannel )apping0......................................................................................................2!
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!.%.2 Do$nlink ,hannel )apping0.................................................................................................2%
+ GPRS ,e" Technoo!ies#############################################################################################################################$-
".1 3oS *mplementation..........................................................................................................................24
".2 )edia 5ccess ,ontrol -)5, (ayer................................................................................................24
".2.1 Radio lock Structure............................................................................................................!+
".2.2 ,hannel ,oding......................................................................................................................!2
".2.! lo$ ,ontrol...........................................................................................................................!%
".2." ,ell Selection and Reselection...............................................................................................!6
. EDGE Technoo!"#######################################################################################################################################+0
%.1 Definitions........................................................................................................................................."+
%.2 eatures.............................................................................................................................................."+
%.! Specifications....................................................................................................................................."1
%." 7ey &echnologies.............................................................................................................................."2
%.".1 EDGE )odulation )odes......................................................................................................"2
%.".2 EDGE Radio lock Structure................................................................................................."!
%.".! ,hannel ,oding......................................................................................................................""
%."." (ink 3uality ,ontrol.............................................................................................................."6
%.".% Dynamic 8indo$ Si9e..........................................................................................................."'
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1 GPRS Technology
1.1 GPRS Definition
GPRS is a packet data ser:ice introduced in GS) Phase2;. GPRS pro:ides
suscriers the end
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GPRS pro:ides solutions to implement data ser:ices in GS) technologies and
current net$orks. GPRS can sa:e in:estment and makes Auick returns.
1.3 GPRS Specifications
*n Europe= it $as suggested in 144! for GPRS to e deployed in GS) net$ork. *n
144'= great progress $as made in GPRS standardi9ation. *n @ctoer 144'= E&S* issued
GPRS Phase1 ser:ice description. GPRS phase 2 $as completed at the end of 1444.
GPRS standard goes through three phases. *n order to implement GPRS= 1B ne$
standards are made and many standards are modified three phases.
&ale 1.!
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$ GPRS %et&ork 5rchitecture
Gn= G= Gr= Gp= Gs= and Gi interfaces
P&P and roaming security guarantee
,harging
@perator
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GF&+!FE1F+ GPRS and EDGE asic
BSC MSC/VLR SMC
PCU
Charginggateway
function (CGF)
Billing syste
!LR
Signaling an" GPRS su#scri#er "ata
Signaling
Pac$et "atanetwor$
SGS%
Gs interface
Gn interface
SGS%
GGS%
G" interface
Gr interface
Gc interface
Gn interface
Gi interface
G# interface
Gainterface
Ga interface
ig 1."
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$ GPRS %et&ork 5rchitecture
SGS#. &he SGS# resumes the GPRS connection after recei:ing the message.
&hus= the )S need not to estalish GPRS connection repeatedly. )ost of the
GPRS )S types in current market are type
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GF&+!FE1F+ GPRS and EDGE asic
&hrough G&P= Suscrier data and signaling et$een GPRS Support #odes
-GS# are transmitted in GPRS ackone net$ork. 5ll point
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$ GPRS %et&ork 5rchitecture
*n SS= relay transfers ((, PDUs et$een Um interface and G interface. *n
SGS#= relay transfers PDP PDUs et$een G interface and Gn interface.
SS GPRS Protocol -SSGP
&his layer transfers the information related to routing ser:ice Auality et$een
SS and SGS#. SSGP does not pro:ide error correction function. GS)+B.1B
pro:ides SSGP specifications.
#et$ork Ser:ice -#S
&his layer transfers SSGP PDUs. #S is ased on the frame relay connection
et$een SS and SGS#. *t pro:ides multi
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GF&+!FE1F+ GPRS and EDGE asic
G))/S) refers to GPRS moility management and session management. )S0
"ownlin$ &'3essage 5 &'3essage5
B4 B B, ,4 B0 B5 B- , B6 B7 B8 ,, B9 B4 B ,0
-,3ultifrae nu#er n1-:
ulin$&'>4&'>
"ownlin$&'3essage 0 &'3essage
0
B4 B B, 6 B0 B5 B- 7 B6 B7 8 B9 B4 B 9
-,3ultifrae nu#er n15:
ulin$&'>8&'>9
"ownlin$&'3essage 0 &'3essage
0
B8
"ownlin$
&'3essage &'3essage
B4 B B, 4 B0 B5 B- B6 B7 B8 , B9 B4 B 0
-,3ultifrae nu#er n:
ulin$&'>4&'>
B4 B B, 5 B0 B5 B- - B6 B7 B8 6 B9 B4 B 7
-,3ultifrae nu#er n1:
ulin$&'>,&'>0
"ownlin$&'3essage &'3essage
-,3ultifrae nu#er n1,:
ulin$&'>5&'>-
"ownlin$&'3essage , &'3essage
,
BB4 B, 8 B0 B5 B69B- B7 B8 4 B9 B4 B
B4 B B, , B0 B5 B- 0 B6 B7 B8 5 B9 B4 B -
-,3ultifrae nu#er n10:
ulin$&'>6&'>7
"ownlin$&'3essage , &'3essage
,
ig !.%
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GF&+!FE1F+ GPRS and EDGE asic
3.".2 Donlin! Channel &apping6
PD&,/D and P5,,/D mapping0
)S interprets e:ery do$nlink lock on the allocated PD, and determines
$hether the lock is its PD&,/D and P5,,/D according to &*.
& is a physical connection used y t$o RR entities to transmit ((, PDU in a
unidirectional manner on packet data radio channel.&his parameter is used in
((, frame transmission seAuence of the same timeslot in same cell to replace
)S identification in R(,/)5, layer. *t is radio resource assigned to one or
multiple PD,s. *t transmits R(,/)5, locks carrying one or multiple ((,
PDUs.&he & is temporary and only kept in data transmission -the & is
kept until there is no R(,/)5, lock to transmit= or all the R(,/)5, locks
are recei:ed successfully y the recei:er under the R(, ackno$ledgement
mode.
or each &= net$ork allocates a &*.or concurrent &s in each direction=
&* allocated is uniAue. *t is used to replace )S identifier in R(,/)5, layer.
&he same &* can e used in different directions.&* is assigned in the resource
allocation message efore transmission of ((, frame.
R(,/)5, lock related to a specific & must contain a &*. or a R(, data
lock= the & is Hointly identified y the &* and the transmission direction of
the data lock. or a R(,/)5, control message= there are transmission
direction and message type in addition to the &*. *f the header of a do$nlink
control lock contains a &*= the &* identifies to $hich )S the control message
is sentK other$ise= all )Ss $ill recei:e this message. *f the &* in the header is
inconsistent $ith that in the message= the )S accepts the &* in the header.
P,, mapping and packet system message transmission0
*n a cell= P,, is mapped to one PD, only. Specific location is roadcast
y ,,. *n a %2
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$ GPRS %et&ork 5rchitecture
of messages to e sent.
System parameter PS*1FREPE5&FPER*@D determines the position $here PS*1is sent. *n addition= ecept PS* 1= other PS*s are di:ided into t$o groups. @ne
group is sent at a high repetition rate= $hile the other is sent at a lo$ repetition
rate.Parameter PS*F,@U#&FR indicates the numer of PS*s sent at a high
repetition rate= and PS*F,@U#&F(R indicates the numer of PS*s sent at a lo$
repetition rate.
System sends PS*s according to the follo$ing rules0
PS* 1 is sent on (@,7 + $hen &, is +. -&, I -# D* %2 mod
PS*1FREPE5&FPER*@D.
8hen SFP,,F(7S is higher than 1= PS* 1 is also sent on (@,7 6
$ith &, of +.
PS*s in the group sent at a high freAuency are sent in seAuence determined y
net$ork. &he seAuence starts $hen &, is +K that is= sending cycle of PS*s in this
group is PS*1FREPE5&FPER*@DN%2 frame. 8hen PS*s in this group are sent=
P,, (@,7s= $hich are not occupied y PS*s= $ill e used.
PS*s sent in the group sent at a lo$ freAuency are sent in the seAuence
determined y the net$ork= and sent repeatedly. 8hen the PS*s in this group are
sent= the P,, (@,7s= $hich are not occupied y PS*s= $ill e used.
Do$nlink P,,, mapping
Do$nlink P,,, mapping on a PD, can e descried y the follo$ing four
rules0
SFP,,F(7S locks are used in the P,, if PD, has a P,,.
SFP5GF(7SFRES locks cannot e used in the PP, in the remaining
locks. &hey can e used in the P5G,= P#,= PD&, and P5,, only.
&he remaining locks can e used in the PP,= P5G,= P#,= PD&, and
P5,,.
8hen P,, is on timeslot k= the P,,, can e located on timeslot n only=
and n must e greater than k
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GF&+!FE1F+ GPRS and EDGE asic
kno$n according to the lock seAuence -+= 6= != 4= 1= '= "= 1+= 2=
B= %= and 110
P,,s are located on + and 6.
PP, can e located on 1+= 2= B= %= and 11 only.
P5G,= P#,= PD&,= and P5,, can e located on != 4= 1= '= "=
1+= 2= B= %= and 11.
28
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@n the do$nlink -for eample= the )S= )5, layer has the access reAuests Aueue and
makes an access time tale. or do$nlink= contention mechanism is unnecessary
ecause there is only one transmit end in do$nlink direction.
)5, layer assigns data to e sent $ith different priority and transmits data according
to priority. Signaling data has higher priority than suscrier data. 5fter comined=
signaling and suscrier data are sent through transmission media. )5, layer enales
se:eral )Ss to share same transmission medium. &ransmission medium can e a
physical channel or se:eral physical channels. *n &D)5= physical channels are &D)5
timeslots.
8hen se:eral physical channels ser:e as transmission media= )S sends dataconcurrently. *t can increase the data transmission capacity et$een )S and net$ork.
See the eample as sho$n elo$ in ig ".2
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GF&+!FE1F+ GPRS and EDGE asic
)ade up of one it= 5, indicates $hether the header of the do$nlink
R(,/)5, control lock contains optional &*/D field. >+? indicates &*/D field
is contained= and >1? not.
Direction -D it
)ade up of one it= D it indicates & direction. & is identified y &* field
in do$nlink R(,/)5, control header. *f D it is += & identified y &* is
uplink. *f it is 1= & is do$nlink.
4.2.2 Channel Co*ing
GPRS defines four coding modes on PD&,0 ,S
#loc$
co"e
Ra"io #loc$
no co"ing
5-6#its
ig ".2
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$ GPRS %et&ork 5rchitecture
,oding procedure is as follo$s0
1. 5dd a lock ,heck SeAuence -,S to the end of the radio lock for errordetection.
2. Perform pre!. Punch to otain desired coding rate.
Error&ale ".2
Procedure&ype
,S1 ,S2 ,S! ,S"
(ength of data
source1B" its 2'1 its !1% its "1! its
Packet coding
-1 ire coding. &he
multinomial generated
is0
-D2!;1-D1';D!;1.
&he ,S added is "+
its.
-2 5dd four tail its.
&he coding data
length is 22B its.
-1 Packet coding. &he
multinomial generated
is0
D16
;D12
;D%
;1. &headded ,S is 16 its.
-2 US preprocessing.
See&ale ".2
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GF&+!FE1F+ GPRS and EDGE asic
&ale ".2
,S
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$ GPRS %et&ork 5rchitecture
,hannel
&ype
*nput
Rate-kit/s
*nput ,ode
lock -its
,ode @utput
,ode
lock
-its
*nterlea:ing
Depth,heck it
US
Precod
ing
&ailit
,on:olutio
nal
,ode Rate
P5G,=
P#,=
P,,=
P5,,
coding= "+consecuti:e
ursts
4.2.3 Flo Control
*t controls the 3oS delay Aueue load et$een SGS# and SS to optimi9e the use of
uffer area.
SSGP layer P,U manages t$o uffers $hich are )S uffer and SSGP irtual
,onnection -, uffer. 8hen P,U recei:es a ((, packet= its SSGP protocol layer
identifies it according to &((* and places it into )S uffer. &hen= SSGP protocol
layer uses ,* as identifier and places all related information into the uffer for that
,.
See ig ".2
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$ GPRS %et&ork 5rchitecture
4.2.4.2 Cell Reselection
GPRS net$ork or )S control ,ell reselection process. *n net$ork controlled cell
reselection process utili9es cell load= status= le:el and other information in optimi9ed
manner.
#et$ork
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$ GPRS %et&ork 5rchitecture
cell= and sends the cell reselection indication to the RP. )ean$hile= it sends the
cell reselection indication to the RP $here the target cell is located. &hus= after
the cell reselection of the )S= the ne$ cell can perform cell reselection control
o:er it rapidly.
Send cell reselection command.
5fter recei:ing the cell reselection indication= the RP sends the cell reselection
command to the )S. Under the packet idle status= if P,,, is configured= the
cell reselection command is sent to the )S on P,,,. *f there is no P,,,= a
do$nlink lock is assigned on ,,, :ia the immediate assignment message.
&he cell reselection command is sent in the do$nlink lock assigned. Under thepacket transmission status= the cell reselection command is sent to the )S on
P5,,. ,!1 and ,!2 are used to select the optimal cell= and the last selection is
not made here in the pre
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GF&+!FE1F+ GPRS and EDGE asic
" 'DG' Technology
".1 Definitions
Enhanced Data for GS) E:olution -EDGE includes Enhanced General Packet Radio
Ser:ice -EGPRS and Enhanced ,ircuit S$itched Data -E,SD. EDGE is a method
used to impro:e the data transmission rate during GS) radio connection.
Essentially= EDGE is only a ne$ modulating and channel encoding technology= $hich
can e used to transmit Packet s$itching -PS and ,ircuit S$itching -,S data/:oice.
5s an e:ol:ed GPRS
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$ GPRS %et&ork 5rchitecture
communication control layer= and communication connection layer. &he
interface et$een layers is standard. &he hierarchical architecture makes the call
control and communication connection mutually independent. *t also fully uses
ad:antages of the packet s$itching net$ork= making the and$idth allocation
closely related to the traffic. *t especially suits the o*P ser:ice.
)edia Gate$ay -)G8 is adopted in EDGE. )G8 has the same functions as
Signaling &ransfer Point -S&P= and can reali9e the signaling net$ork
estalishment in *P net$ork. )oreo:er= )G8 is not only the interface et$een
GS) circuit s$itching ser:ice and PS ut also the interface et$een Radio
5ccess #et$ork -R5# and !G core net$ork.
EDGE supports t$o data transmission modes0 packet s$itching and circuit
s$itching. 8ith the packet data ser:ice= a rate of 11.2 kps 64.2 kps per
timeslot can e reali9ed. EDGE supports the circuit s$itching ser:ice $ith a rate
of 2B.B kps. EDGE also supports symmetric/asymmetric data transmission=
$hich is :ery important for the moile eAuipment to access net$ork. or
eample= in EDGE system= the user can ha:e a higher rate in do$nlink than in
uplink.
".3 Specifications
&he EDGE standardi9ation in:ol:es the follo$ing three aspects0
Standardi9es the rele:ant change in physical layer -the definition of modulation
and coding method
Standardi9es the change in E,SD protocol
Standardi9e the change in EGPRS protocol
&$o Hos are done in the ao:e aspects0
EDGE #SS= $hich is related to the change in net$ork susystem
EDGE SS= $hich is related to the change in ase station susystem
EDGE is reali9ed in t$o phases0
Phase 10 pro:ides the single/multiple
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GF&+!FE1F+ GPRS and EDGE asic
Phase 20 pro:ides real
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GF&+!FE1F+ GPRS and EDGE asic
data lock. *n EGPRS= the radio lock transferring data is composed of one )5,/R(,
header and one or t$o R(, data locks. &he ,S is used for the error check of the
head and the ,S is used for the error check of the data.
,ompared $ith GPRS radio data lock= the EGPRS radio data lock has the follo$ing
features0
Phase 10 pro:ides single
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$ GPRS %et&ork 5rchitecture
e added after the payload.
amily 0 &he payload of family code has 2B ytes. *t corresponds to ),S
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GF&+!FE1F+ GPRS and EDGE asic
22."
24.6
"".B
%"."
%4.2
G)S7
B
1'.6
G)S7
,S
under G)S7 modulation mode at lo$ rate is more suitale at the edge of a cell to
compensate the poor link Auality. *n the central area of a cell $ith good transmission
conditions= an ),S $ith high rate can e used.
".4.4 %in! 8uality Control
".4.4.1 %in! $*aptation
EGPRS allo$s re
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$ GPRS %et&ork 5rchitecture
has more po$erful anti
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GF&+!FE1F+ GPRS and EDGE asic
-see GS)+".6+.
&hat the $indo$ si9e can change $ith the multi
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$ GPRS %et&ork 5rchitecture
8indo$ Si9e ,oding&imeslots 5llocated -)ulti